[stubs] An easier way of defining a stub call interface descriptor.

src/interface-descriptors.h

Index: src/interface-descriptors.h
diff --git a/src/interface-descriptors.h b/src/interface-descriptors.h
index b7c6c9db8450818000bed40c80726d8a15284fca..3239a55f5f367bbb9045f30c95f0a52402eefa19 100644
--- a/src/interface-descriptors.h
+++ b/src/interface-descriptors.h
@@ -109,7 +109,7 @@ class CallInterfaceDescriptorData {
   // and register side by side (eg, RegRep(r1, Representation::Tagged()).
   // The same should go for the CodeStubDescriptor class.
   void InitializePlatformSpecific(
-      int register_parameter_count, Register* registers,
+      int register_parameter_count, const Register* registers,
       PlatformInterfaceDescriptor* platform_descriptor = NULL);
 
   bool IsInitialized() const { return register_param_count_ >= 0; }
@@ -218,6 +218,12 @@ class CallInterfaceDescriptor {
     }
   }
 
+  // Initializes |data| using the platform dependent default set of registers.
+  // It is intended to be used for TurboFan stubs when particular set of
+  // registers does not matter.
+  static void DefaultInitializePlatformSpecific(
+      CallInterfaceDescriptorData* data, int register_parameter_count);
+
  private:
   const CallInterfaceDescriptorData* data_;
 };
@@ -229,6 +235,17 @@ class CallInterfaceDescriptor {
   }                                                        \
   static inline CallDescriptors::Key key();
 
+#define DECLARE_DEFAULT_DESCRIPTOR(name, base, parameter_count)            \
+  DECLARE_DESCRIPTOR_WITH_BASE(name, base)                                 \
+ protected:                                                                \
+  void InitializePlatformSpecific(CallInterfaceDescriptorData* data)       \
+      override {                                                           \
+    DefaultInitializePlatformSpecific(data, parameter_count);              \
+  }                                                                        \
+  name(Isolate* isolate, CallDescriptors::Key key) : base(isolate, key) {} \
+                                                                           \
+ public:
+
 #define DECLARE_DESCRIPTOR(name, base)                                         \
   DECLARE_DESCRIPTOR_WITH_BASE(name, base)                                     \
  protected:                                                                    \
@@ -424,10 +441,7 @@ class HasPropertyDescriptor final : public CallInterfaceDescriptor {
  public:
   enum ParameterIndices { kKeyIndex, kObjectIndex };
 
-  DECLARE_DESCRIPTOR(HasPropertyDescriptor, CallInterfaceDescriptor)
-
-  static const Register KeyRegister();
-  static const Register ObjectRegister();
+  DECLARE_DEFAULT_DESCRIPTOR(HasPropertyDescriptor, CallInterfaceDescriptor, 2)
 };
 
 class TypeofDescriptor : public CallInterfaceDescriptor {